1. Field of the Invention
The present invention is directed to a page buffer of a flash memory device and more particularly, a page buffer circuit capable of reducing a program error.
2. Discussion of Related Art
In general, program verifications whether data is exactly programmed or not are performed after programming data in NAND-type flash memory devices. If data is not programmed, it is programmed once more. To the contrary, if data is programmed, next operation is performed.
In this progress, if a passed cell at first is influenced by an external factor, or if the program verification is performed without a margin of threshold voltage, a previous passed cell would be failed. Thus, a cell with increased threshold voltage is programmed again, and thereby more increasing the threshold voltage of a cell so that a program error may occur.